This invention, in general terms, relates to mine ventilation, and more particularly to:
(a) an overcast structure for the intersection of two passageways or airways in a mine, air flowing in each airway for ventilation, the installation as completed by-passing air flowing in one airway around the other at their intersection to avoid interference of the flows; PA1 (b) the installation as completed at the intersection of the intersecting airways; and PA1 (c) the method of installation.
Reference is made to the coassigned U.S. Pat. No. 5,412,916 of William R. Kennedy and John M. Kennedy, dated May 9, 1995 entitled "Structure Having Quick-Connect Components" and the coassigned U.S. Pat. No. 5,466,187 of John M. Kennedy and William R. Kennedy, dated Nov. 14, 1995 entitled "Mine Ventilation Structure" for background, the second of these patents (the '187 patent) containing what is believed to be an ample discussion of what is meant by the term "overcast" and reasons for the installation of an overcast in a mine.
As described in said '187 patent, the installation of the preferred embodiment thereof involves first, the positioning of wing panels 30 in the first of the two intersecting passageways, followed by the erection of corresponding sections of side wall panels to form portions of the side walls 24 of the overcast tunnel 18. A deck 28 is applied simply resting at its ends on the side walls and end panels 32 are installed. While the procedure has generally been quite satisfactory and extensively used, and as described in said '187 patent may be erected quickly by only a few laborers who need no special knowledge of overcast instruction, it is still quite labor intensive.
While said '187 patent states (in column 3, lines 43-47 thereof) that either or both of the steel ends and wings may be omitted entirely by sizing the tunnel width to equal the mine entry width and/or the tunnel height to equal the mine entry height, this still entails the need of relatively intensive labor procedure in the mine.